The transition of a submarine from deep under the ocean surface to periscope depth can place both the submarine and surface craft at risk. As evident by the incidents involving the U.S.S. Greenville and the U.S.S. Jacksonville submarines, the present procedures using passive sonar and the submarine's periscope do not always avoid submarine/surface craft collisions.
The existing practice on board U.S. submarines preparing to surface is to check for existing contacts using passive sonar. If any contacts are determined to be near the submarine and present a possibility of counter-detection or collision, no excursion is made to periscope depth. If no contacts present a risk, the submarine then proceeds to periscope depth. The primary risk to the submarine coming to periscope depth in a littoral environment is a quiet surface contact such as a fishing vessel or pleasure craft. When surface contacts are not detectable due to the silence of the contact (e.g., a sailboat) or due to water conditions (e.g., a surface layer), the submarine's first detection of a contact can very well be the moment the periscope breaks the water surface.
In the prior art, one attempt was made to produce a camera buoy launched from the submarine's three inch counter-measure launcher. The single unit was built by General Dynamics as an experimental addition to the original non-penetrating mast (NPP) digital periscope program. The system as envisioned by General Dynamics used an expendable three inch diameter buoy with a gyro-stabilized optic assembly. This attempt was unsuccessful, however, because of the very low height-of-eye of the buoy due to the weight of the mechanical image stabilization subsystem and the limitation of the package to the dimensions of an unmodified three inch launcher. Also, the very short copper wire tether used to transmit the video signal prevented full deployment of this system.
Also in the prior art, attempts were made to place a camera on a submarine aimed up at the ocean surface. This system, however, does not work when the depth of the submarine is beyond a certain limit, when the water is murky, when it is cloudy or dark, or when large waves are present on the ocean's surface.